Prevalence of fluoroquinolone-resistance markers, and dual-class-resistance markers, in asymptomatic men who have sex with men.

Failure of fluoroquinolones, the principal treatment option for macrolide-resistant infections, has recently emerged. This is of particular concern for men who have sex with men (MSM), who have high proportions of macrolide-resistant infections. Treatment failure with moxifloxacin is likely the result of single nucleotide polymorphisms (SNPs) in , whilst concurrent mutations may play a role. The levels of fluoroquinolone resistance and dual-class (i.e. macrolide and fluoroquinolone) resistance in among asymptomatic MSM is unknown. To (i) determine the proportion of fluoroquinolone resistance and dual-class resistance in infections among asymptomatic MSM, (ii) explore any clinical and behavioural associations with fluoroquinolone resistance, and (iii) determine the distribution of antibiotic resistance among sequence types (STs). positive samples (=94) were obtained from 1001 asymptomatic MSM enrolled in a study at Melbourne Sexual Health Centre (Carlton, Australia) between August 2016 and September 2017. Sanger sequencing was performed to determine the proportion of infections with SNPs in that have previously been associated with failure of moxifloxacin (corresponding to amino changes S83I, D83R, D87Y and D87N) and in (corresponding to amino acid changes M95I, D99N, D99Y and D99G). Associations between clinical/behavioural factors and SNPs were examined. Strain typing was performed by sequencing a portion of the gene. The proportion of MSM with infections harbouring and SNPs was 13.0 % [95 % confidence interval (CI): 6.8-23.2 %] and 4.7 % (95 % CI: 1.1-13.4 %), respectively; dual-class resistance was 13.0 %. No significant clinical/behavioural associations were found. Antibiotic resistance was not restricted to specific STs. One in eight (13 %) of asymptomatic MSM with had an infection with dual-class-resistance mutations. Typing by sequence suggested fluoroquinolone resistance is arising from independent mutation events. This study illustrates that asymptomatic MSM may act as a reservoir for antibiotic-resistant .